Residency Migration Reference
Moving from Illinois to Idaho: Residency, Taxes, and What to Prove
Illinois's 4.95% (flat) top income tax rate becomes 5.30% in Idaho. This move trades a lighter tax environment for a heavier one, so timing income around the transition year matters.
Residency Tests Side by Side
Illinois does not use a simple day-count threshold; it applies a facts-and-circumstances test instead. Idaho's statutory residency test uses a 270-day threshold.
| Factor | Illinois | Idaho |
|---|---|---|
| Statutory Residency Test | Illinois has no statutory residency test of the New York or Minnesota type: no bright-line day count and no permanent place of abode prong. 35 ILCS 5/1501(a)(20)(A) defines a resident as an individual '(i) who is in this State for other than a temporary or transitory purpose during the taxable year; or (ii) who is domiciled in this State but is absent from the State for a temporary or transitory purpose during the taxable year.' Those are the only two routes to Illinois residency for an individual. Cain v. Hamer, 2012 IL App (1st) 112833, shows how far that departure from a day count runs: snowbird retirees who spent 1,666 days in Illinois against 1,700 in Florida across 1996 through 2004, an average well above 183 Illinois days a year, were held not to be Illinois residents. Day counts matter in Illinois as evidence of purpose and as inputs to the administrative presumptions, not as a threshold that decides residency by itself. | Idaho Code §63-3013 defines a resident as an individual either domiciled in Idaho for the entire taxable year, or someone who maintains a place of abode in Idaho for the entire taxable year and spends in the aggregate more than 270 days of the taxable year in Idaho, a materially higher threshold than the 183-day test most states use. Presence within the state for any part of a calendar day counts as a full day toward that 270-day total. |
| Domicile Test | Illinois follows the traditional common-law domicile standard under 86 Ill. Adm. Code 100.3020: domicile is the place a person intends as their true, fixed, permanent home, and to which they intend to return whenever absent. A person can have only one domicile at a time, and it continues until a new one is established through both physical presence in the new location and demonstrated intent to abandon Illinois as the permanent home. The Department of Revenue looks at where a person votes, holds a driver's license and registers vehicles, banks, keeps professional relationships (doctor, lawyer, accountant), works, houses family, and belongs to clubs or religious institutions; no single factor controls. | Idaho defines domicile administratively (IDAPA 35.01.01.030 and the Tax Commission's public guidance) as the place that is the center of an individual's personal and business life, the permanent home a person intends to return to whenever absent. An individual can have multiple residences but only one domicile at a time, and once established, domicile persists until it is affirmatively abandoned, a new one is acquired, and the person is actually living in the new domicile. Evidence weighed includes where the family lives, comparison of homes in different states, where business activity occurs, how time is actually spent during the year, where sentimentally important belongings are kept, and whether the person has given up an Idaho driver's license or the Idaho homeowner's exemption. |
| Day Count Threshold | No fixed threshold | 270 days |
| Any Part of a Day Rule | Not applicable in the statutory sense, because Illinois has no day-count threshold for an individual to cross. There is no any-part-of-a-day rule to apply. Days still get counted in Illinois practice, both because 86 Ill. Adm. Code 100.3020(f) presumes residency above nine months in the aggregate and presumes continued residency where an individual is present in Illinois more days than in any other state, and because the Department of Revenue's audit division reconstructs presence from credit card, toll, and travel records to test whether time in Illinois was temporary or transitory. | Yes. Idaho Code §63-3013(1)(b) explicitly states that presence within the state for any part of a calendar day counts as a full day toward the 270-day aggregate threshold, the strict any-part-of-a-day standard. |
| Presumptions | 86 Ill. Adm. Code 100.3020(f) supplies four rebuttable presumptions in place of a statutory day test. An individual who spends in the aggregate more than nine months of any taxable year in Illinois is presumed to be a resident. An individual absent from Illinois for one year or more is presumed to be a nonresident. An individual receiving a homestead exemption on Illinois property under 35 ILCS 200/15-175 is presumed to be an Illinois resident. And an Illinois resident in one year is presumed to be a resident the following year 'if he or she is present in Illinois more days than he or she is present in any other state.' The presumptions 'are not conclusive and may be overcome by clear and convincing evidence to the contrary,' with the rule listing acceptable rebuttal evidence including location of spouse and dependents, voter and vehicle registration, driver's license, filing a resident return elsewhere, home ownership or rental agreements, the permanent or temporary nature of work assignments, location of professional licenses, location of medical providers, accountants and attorneys, club memberships and participation, and telephone or other utility usage over a duration of time. | None published as a separate presumption distinct from the domicile-plus-270-day statutory test; Idaho instead runs its 445-day absence safe harbor (below) as the primary mechanism for domiciled Idahoans to be treated as nonresidents. |
| Safe Harbors | None published | 445-day absence exception |
Leaving Illinois
Illinois is not in the top tier of aggressive exit-audit states the way New York or California are, but the Department of Revenue does examine departing high earners, especially where a large capital gain or business sale occurred near the claimed move date, or where the taxpayer kept an Illinois home, spouse, or business presence after claiming nonresidency. Auditors reconstruct day counts using credit card statements, toll records, airline records, and utility usage, and they cross-check the General Homestead Exemption against a claimed out-of-state domicile.
Trailing Income
Illinois does not have a convenience-of-the-employer rule, so a former resident who telecommutes for an Illinois employer from another state generally is not taxed by Illinois on those wages solely because the employer is based in Illinois; sourcing follows where the work is actually performed. Illinois does tax nonresident income that is Illinois-source, including compensation for services actually performed in Illinois, gain on the sale of Illinois real property, and a departing resident's share of Illinois business income allocated under the state's apportionment rules for the period they were still a resident or doing business in the state.
Part-Year Filing
Form IL-1040 together with Schedule NR, Nonresident and Part-Year Resident Computation of Illinois Tax, is used for the year someone moves into or out of Illinois. Schedule NR allocates income between the Illinois-resident portion of the year and the nonresident portion, and computes an Illinois tax based only on Illinois-source and Illinois-period income.
Enforcement Methods
Common Exit Mistakes
Establishing Idaho Residency
| Action | Agency | Deadline |
|---|---|---|
| Get an Idaho driver's license | Idaho Transportation Department | within 90 days of becoming an Idaho resident |
| Title and register vehicles in Idaho | Idaho Transportation Department / county assessor's motor vehicle office | within 90 days of moving to Idaho |
| Register to vote | Idaho Secretary of State / county clerk | 11 days before an election for mail or online registration; same-day registration is available at early voting locations and on Election Day with proof of residency |
Declaration of Domicile
Idaho has no formal declaration-of-domicile filing comparable to Florida's. The Tax Commission's own guidance points to concrete, checkable evidence instead: where your family lives, where you do business, how you actually spend your time during the year, where sentimentally important belongings are kept, and whether you've obtained an Idaho driver's license or filed for the Idaho Homeowner's Exemption.
Homestead
Idaho's Homeowner's Exemption (Idaho Code §63-602G) exempts 50% of a primary residence's assessed value, capped at $125,000, from property tax, but requires an affirmative application with the county assessor rather than applying automatically. It lasts only until ownership changes or the home stops being used as the owner's primary residence, so a person who moves out but forgets to cancel the exemption leaves an easy paper trail contradicting a claimed departure.
Voter Registration
Mail and online registration must be received 11 days before an election; Idaho also permits same-day registration in person at early voting locations and on Election Day with proof of residency. https://voteidaho.gov/voter-registration/
Vehicle Registration Deadline
90 days
New Resident Tax Traps
Idaho taxes worldwide income from the date Idaho domicile begins, requiring the Form 43 part-year apportionment for the year of the move. Because Idaho and Washington are both community property states, a couple where one spouse lives and works in Idaho and the other in Washington must generally report one-half of all community income, including the out-of-state spouse's earnings, on the Idaho return, a wrinkle that surprises newly arrived couples who assume only Idaho-source income is reportable.
What Changes on Tax
Illinois Top Rate
4.95% (flat)
Idaho Top Rate
5.30%
Moving from Illinois to Idaho raises the top marginal income tax rate from about 4.95% to about 5.3%, an increase of roughly 0.35 percentage points.
Withholding Reciprocity
Illinois and Idaho do not have a wage-withholding reciprocity agreement with each other, so this move follows ordinary source-state and resident-state filing rules rather than a reciprocity exception.
Community Property Transition
Illinois uses common law marital property rules and Idaho is a community property state. Property acquired during marriage after the move may be characterized differently going forward, which matters for estate planning and for basis step-up on a spouse's death.
Beyond Income Tax
Illinois
Capital gains: No preferential rate. Capital gains are taxed as ordinary income at the same 4.95% flat rate as wages.
Estate or inheritance tax: Illinois has an estate tax with a $4 million exemption per estate that is not indexed for inflation and is not portable between spouses. Rates are graduated from roughly 0.8% up to 16% on the amount above the exemption. There is no separate inheritance tax.
Property tax: Illinois has the highest statewide effective property tax rate in the country, around 1.92% of home value, more than double the national median. The General Homestead Exemption reduces the taxable assessed value of an owner-occupied principal residence by up to $10,000 in Cook County, $8,000 in counties bordering Cook, and $6,000 elsewhere.
Sales tax: State base rate is 6.25%, but local home-rule and county taxes push combined rates as high as 11.5% in parts of Cook, Kane, and Warren counties; the effective statewide average is closer to 8.9%.
Idaho
Capital gains: Taxed as ordinary income at the flat rate, but Idaho allows a deduction of 60% of the net capital gain from the sale of qualifying Idaho property under Idaho Code §63-3022H. Qualifying property generally means Idaho real property held at least 12 months (18 months if sold before January 1, 2005), or certain business assets, cattle, and horses held for the required period; the deduction is claimed on Form CG and does not apply to gains on out-of-state property or most financial assets.
Estate or inheritance tax: None. Idaho has no estate tax and no inheritance tax.
Property tax: Effective rate is roughly 0.50% of value. Idaho's Homeowner's Exemption exempts 50% of a primary residence's assessed value up to a $125,000 cap (Idaho Code §63-602G), but unlike an automatic homestead protection this requires an affirmative application with the county assessor and lasts only until ownership changes or the home stops being the owner's primary residence, making it an easy domicile cross-check point.
Sales tax: 6.00% state rate, with a low average combined state-and-local rate of about 6.03%, since Idaho has very limited local-option sales taxes (mostly a handful of resort cities).
Who This Move Applies To
Travel Nurses
In Illinois
Illinois has no statutory day-count test to trip, so a travel nurse not domiciled in Illinois does not become an Illinois resident merely by crossing a day threshold on a long assignment. What creates exposure instead is the temporary or transitory question and the 100.3020(f) presumptions: an assignment structured as a series of renewals that keeps a nurse in Illinois more than nine months of a year, or more days than in any other state, supports a presumption of residency that must be rebutted by clear and convincing evidence, and the permanent or temporary nature of the work assignment is named in the rule as relevant evidence. The more common Illinois exposure is the reverse pattern, where a nurse claims a Florida or Texas tax home but actually lives in and pays Illinois-area rent for most of the year; Illinois-source wages for days actually worked in Illinois are taxable to any nonresident nurse regardless of claimed tax home.
In Idaho
Boise's hospital systems and Idaho's rural-hospital travel contracts make the state a modest but real travel-nurse market. A nurse genuinely domiciled in Idaho who takes Idaho contracts is simply taxed as a resident. A nurse claiming an Idaho tax home while working elsewhere needs a real, regularly used, duplicated-expense Idaho residence; claiming Idaho as a federal away-from-home tax home while also trying to use the 445-day absence exception for Idaho state tax purposes is explicitly disqualifying under Idaho's own rule, so the two claims cannot be made consistently.
Professional Athletes
In Illinois
Illinois taxes nonresident professional athletes on a duty-day basis: Illinois-source income equals total compensation multiplied by the ratio of duty days in Illinois (games, practices, mandatory team functions) to total duty days for the season; mere travel through Illinois without a game or team event does not create a duty day. This applies to visiting teams playing the Bears, Bulls, Blackhawks, White Sox, and Cubs, and Illinois is regarded by practitioners as an aggressive, well-enforced jock-tax state that historically extended the tax reciprocally to any state that taxed Illinois-based athletes.
In Idaho
Idaho has no major professional sports franchise in the four big US leagues, so jock-tax exposure runs almost entirely one direction: Idaho-domiciled or Idaho-resident athletes are taxed on income earned while playing in other states under those states' own apportionment rules, and nonresident athletes visiting Idaho for occasional events owe Idaho tax on Idaho-source duty days under the state's standard nonresident income sourcing.
Snowbirds, Long Visitors, and RVers
In Illinois
The Illinois snowbird risk runs entirely through the 100.3020(f) presumptions, not through a day threshold. A retiree who keeps the Illinois house and spends more than nine months there risks the nine-month presumption of residency, and a former Illinois resident is presumed to still be one in the following year if present in Illinois more days than in any other state, which is a comparison a snowbird splitting a year can lose well short of any traditional threshold. The favorable counterweight is Cain v. Hamer, 2012 IL App (1st) 112833, where retirees who split time nearly evenly (1,666 Illinois days against 1,700 Florida days across 1996 through 2004) were held nonresidents, with the court weighing nexus evidence such as Florida licenses, voter registration, a Florida declaration of domicile, club spending, and credit card data showing 73% of expenditures and 61% of transactions outside Illinois. Illinois's General Homestead Exemption is a specific cross-check point if a person claims Florida domicile but keeps the Illinois exemption active.
In Idaho
Idaho's 270-day statutory threshold is unusually generous compared to the 183-day standard most states use, but it comes paired with the strict any-part-of-a-day counting rule, so a snowbird or long-term visitor who owns or leases an Idaho home needs to track every day with any Idaho presence, not just overnight stays, against that 270-day ceiling. Idaho's own seasonal-worker example (a couple splitting time between an Alaska fishing operation and an Idaho off-season home) shows the state applies the ordinary domicile-or-270-day test to seasonal residents just as it would to anyone else, with no special seasonal carve-out.
Remote Workers
In Illinois
Illinois has no convenience-of-the-employer rule. A nonresident who works remotely from another state for an Illinois-based employer is generally not taxed by Illinois on those wages, because Illinois sources employee compensation to where the services are physically performed, not to the employer's location. This makes Illinois meaningfully less sticky for remote workers than New York or a handful of other convenience-rule states.
In Idaho
Idaho has no convenience-of-employer rule: a nonresident performing all work physically outside Idaho for an Idaho-based employer is not Idaho-taxed on those wages. Idaho, particularly the Boise metro area, has drawn a steady stream of remote workers relocating from higher-cost West Coast states since 2020; because Idaho and Washington are both community property states, a remote-working couple split between the two needs to account for the community-property income-sharing rule on their Idaho return, not just source-based sourcing.
Military
In Illinois
Illinois follows the federal Servicemembers Civil Relief Act and Military Spouses Residency Relief Act. A servicemember whose home of record is Illinois remains an Illinois domiciliary for tax purposes regardless of duty station unless they take affirmative steps to change domicile, while a servicemember stationed in Illinois on orders, and their qualifying spouse, does not become an Illinois resident solely because of the posting, and military pay is not Illinois-source income for a nonresident servicemember stationed there.
In Idaho
Idaho follows the federal Servicemembers Civil Relief Act and Military Spouses Residency Relief Act, and Idaho's own guidance walks through the distinction between military home of record and state of legal residence/domicile: a service member stationed in Idaho under orders (for example, at Mountain Home Air Force Base) is taxed based on domicile, not the posting, active-duty military pay is not Idaho-taxed for nonresident service members, and a nonmilitary spouse can independently be a resident, part-year resident, or nonresident depending on their own domicile and MSRRA elections.
Airline Crew
In Illinois
Federal law (49 U.S.C. §40116) limits states to taxing airline employee compensation only in the employee's state of residence and any state where more than 50% of pay is earned. This protects flight crew based at O'Hare or Midway who are domiciled outside Illinois from having their full compensation pulled into Illinois taxation solely because their duty station is in Illinois.
In Idaho
Boise Airport is not a major airline crew base, so Idaho's most relevant federal transportation carve-out runs to interstate rail and motor carrier employees rather than airline crew specifically: Idaho's guidance confirms that employees of interstate rail or motor carriers with regularly assigned duties in more than one state are, under federal law, taxable only in their state of residence, with the Idaho-earned portion of a nonresident's income remaining Idaho-taxable.
Tools for This Move
Illinois to Idaho FAQ
Does Illinois have a 183-day rule like New York or Minnesota?+
No. This is the single most common misconception about Illinois residency. 35 ILCS 5/1501(a)(20) contains no day-count threshold and no permanent place of abode prong; a resident is someone in Illinois for other than a temporary or transitory purpose, or an Illinois domiciliary absent for a temporary or transitory purpose. What Illinois has instead are the rebuttable presumptions in 86 Ill. Adm. Code 100.3020(f), including a presumption of residency above nine months in the aggregate and a presumption that a prior-year resident remains one if present in Illinois more days than in any other state. The practical difference is real in both directions: crossing 183 Illinois days does not by itself make you a resident, and staying under 183 does not by itself make you a nonresident.
Does Idaho use the 183-day rule?+
No. Idaho's statutory residency threshold is 270 days, not 183, and any part of a calendar day with Idaho presence counts as a full day toward that total under Idaho Code §63-3013(1)(b). You're a statutory resident if you maintain a place of abode in Idaho for the entire year and hit that 270-day aggregate, independent of domicile.
If I move to Florida but keep my Chicago condo, will Illinois still tax me?+
Keeping the condo does not by itself make you taxable, because Illinois has no permanent place of abode test that a retained condo could trigger. The risk runs through purpose and presumptions instead. If you spend more than nine months of the year in Illinois, or simply more days there than in any other state after a year as an Illinois resident, the Department gets a presumption of residency you can rebut only by clear and convincing evidence. Continuing to claim the General Homestead Exemption on the condo is worse than the condo itself, since that alone creates its own presumption of Illinois residency and is a cross-check Illinois auditors run directly against a claimed out-of-state domicile.
I'm domiciled in Idaho but working out of state for years. Am I still an Idaho resident?+
Not necessarily, if you qualify for Idaho's 445-day absence exception: being out of Idaho for at least 445 days within a 15-month period lets a domiciled Idahoan be treated as a nonresident. But the exception doesn't apply if your spouse or minor children keep living in your Idaho home more than 60 days a year, or if you claim Idaho as your federal tax home for away-from-home expenses.
Does Illinois have a convenience-of-the-employer rule for remote workers?+
No. Illinois sources employee wages to where the work is physically performed, not to where the employer is headquartered. A nonresident who works remotely from another state for a Chicago-based employer generally is not taxed by Illinois on those wages, which is a meaningful difference from convenience-rule states like New York, and it means remote workers face less Illinois exposure after moving away than they might expect.
How many months can I spend in Idaho as a snowbird before I owe Idaho income tax?+
Up to 270 days in the aggregate during the year, since Idaho's statutory residency test kicks in above that threshold for anyone maintaining an Idaho place of abode. But Idaho counts any part of a day as a full day, so short visits add up faster than in states with a majority-of-day rule.
How do I file my Illinois taxes for the year I move out of state?+
File Form IL-1040 together with Schedule NR, the Nonresident and Part-Year Resident Computation of Illinois Tax. Schedule NR splits your income between the period you were an Illinois resident, which is taxed in full, and the period after you became a nonresident, when only Illinois-source income is taxed. Skipping Schedule NR and simply filing as a full-year nonresident in your move year is a common and easily flagged mistake.
What form do I file if I only lived in Idaho part of the year?+
Form 43, the Idaho Part-Year Resident & Nonresident Income Tax Return. If you and your spouse have different residency statuses and file a joint federal return, you must also file a joint Idaho Form 43, with each spouse's status listed separately.
I work in Illinois but live in Wisconsin. Do I have to file two state returns?+
Illinois has reciprocity with Wisconsin, Iowa, Kentucky, and Michigan, so a Wisconsin resident working in Illinois generally does not owe Illinois tax on those wages and should not have Illinois tax withheld; instead, only Wisconsin taxes that income. If Illinois tax was withheld in error, you file for a refund from Illinois rather than claiming a credit, and you report the income on your Wisconsin return as usual.
Does Idaho tax Social Security?+
No. Idaho fully exempts Social Security benefits from state income tax. Other retirement income like pensions, 401(k), and IRA withdrawals is generally taxed at the flat 5.30% rate, though a separate Retirement Benefits Deduction covers qualifying public-system pensions for taxpayers 65 and older or 62 and disabled.
Will keeping the homestead exemption on my Illinois house hurt me if I claim Florida residency?+
Yes, it's a direct contradiction auditors specifically look for. The General Homestead Exemption requires the property to be your owner-occupied principal residence as of January 1, so continuing to receive it while filing as an Illinois nonresident and claiming Florida domicile undercuts your own position. If you've genuinely moved, removing the exemption is one of the concrete steps that supports your new domicile claim.
Does Idaho have a capital gains tax break?+
Idaho taxes capital gains as ordinary income but allows a 60% deduction on net gains from qualifying Idaho property, generally real property held at least 12 months, claimed on Form CG. The deduction is specific to Idaho property; gains on out-of-state real estate or most stocks and financial assets don't qualify.
Planning the reverse move?
Idaho to Illinois
Moving the other direction is a different fact pattern, not a mirror image. Establishing Illinois residency has its own tests, deadlines, and audit posture.
Start with the Illinois residency guideAlso Consider, Leaving Illinois
Illinois to Idaho Reading
Reviewed Against 32 Primary Sources
ResidencyIQ organizes public residency research into a reviewable reference. It does not provide legal or tax advice. Consult a qualified professional before making a residency decision.
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